Since the invention of the typewriter more than 100 years ago, keyboard engineering has been an active field of research and development, resulting in many competing designs. With the growth of personal computing and telecommunications, the number of keyboard designs has multiplied as designers attempt to accommodate the wide variety of constraints and to exploit opportunities these new technologies present. Nonetheless, much of the variability of prior-art keyboard designs is not due to this variety of constraints and opportunities. Rather, it results from an incomplete appreciation on the part of keyboard designers of the constraints inherent in the problems they are trying to solve. It also reflects the lack of general, effective methods for optimizing with respect to these constraints. The present state of the art is thus represented by a plethora of partial solutions. These ills are cured by the keyboard design methods taught by the present invention. To illustrate the many facets of this invention, the optimizing methods are applied to the design of a variety of device embodiments, each preferred as the substantially optimal solution of a given set of design constraints.
The instant invention relates to touch-typable devices. Touch typing, like playing a musical instrument, is a manual skill which is difficult to learn. Once learned, it is difficult to modify the acquired motor patterns. This difficulty places strong constraints on keyboard design. The familiar Qwerty keyboard (and its close variants such as the Azerty keyboard used in France) owes its dominance to ingraining and overlearning of the motor patterns involved in touch typing. Thus, the wide established base of the Qwerty keyboard has created a barrier to entry to improved keyboards, such as the Dvorak keyboard. Indeed such keyboards have gathered but a limited user community. Due to its large number of keys, the Qwerty keyboard is unsuitable for handheld and smaller typable devices. The advent of such devices opens a niche for keyboard designers. A new design in this niche which becomes dominant will likely conserve its dominant position even if more optimal designs appear later, due to the intrinsic tendency of repetitive motor patterns to become fixed. This prospect imposes an enormous burden of responsibility on keyboard designers to avoid saddling future generations of keyboard users with suboptimal designs.
There are two main approaches in the prior art toward reducing the number of input means required to encode a given set of symbols 1) chording methods, in which a combination of input means are activated to encode each symbol, and 2) ambiguous codes, in which a combination of symbols are encoded by each input means. Chording methods have not met with practical success since they have been heretofore difficult to learn to operate, and few are willing to make the time investment required. Thus, only ambiguous codes, or ambiguous codes in combination with chording methods, hold any real promise as a solution to this problem.